Gloucester will effectively exit the competition if they fail to beat the two-time European champions and Pool Six favourites at a sold-out Kingsholm on Saturday.

And they could hardly face a tougher task just seven days after being demolished on home soil by Aviva Premiership leaders Saracens. It was their sixth Kingsholm loss of the season.

"It will be a massive occasion, a full house and, hopefully, we will be able to raise our game and show some of the good stuff," wing Sharples said.

"We owe our supporters. They deserve better, and it's about time we started producing the goods.

"Munster are one of the top teams in Europe for a reason, but we fronted up well at Thomond Park (in October), and if we do that at Kingsholm there is no reason why we can't get a result."

Gloucester rugby director Nigel Davies has made a number of changes following the dismal 29-8 Saracens defeat, a result that left his team ninth in the Premiership table.

Sharples' fellow wing Shane Monahan makes his first Heineken start of the season, while Jonny May moves from left wing to outside centre and Dan Robson features at scrum-half. In the pack, prop Yann Thomas, hooker Darren Dawidiuk and number eight Gareth Evans all gain call-ups.

Davies said: "The players have acknowledged that they didn't put in the performance that the shirt and the supporters deserve (against Saracens).

"Our main priority is to make sure that we turn up and put in a performance. We are the only ones who can put things right, and I have been pleased with the way the boys have reacted this week. They've been open and honest and driven themselves hard."

Munster welcome back Ireland scrum-half Conor Murray, who has been sidelined for five weeks due to a knee injury, while wing Keith Earls and centre James Downey are also among those returning to action.

"They (Gloucester) have been criticised roundly by their supporters, their public and their ex-players, which is pretty hard to take," Munster head coach Rob Penney said.

"They will be desperate to do well on Saturday, which makes our job that little bit harder."

Harlequins looked down and out following opening Pool Four losses to the Scarlets and Clermont Auvergne, but victory against Clermont in Saturday's return fixture at the Twickenham Stoop would see them keep alive quarter-final hopes.

Former Toulon lock Nick Kennedy makes his full debut for Quins, with wing Ugo Monye and scrum-half Danny Care returning to the back division. Clermont will wrap up the group if they win.

Like Quins, Leicester have little room for manoeuvre as the race for quarter-final places hots up.

The Tigers will be without hooker Tom Youngs and lock Ed Slater for an away Pool Five appointment with Italian side Treviso - Neil Briggs and Sebastian de Chaves are their respective replacements - with victory paramount ahead of next Saturday's likely pool decider against Welford Road visitors Ulster.

Elsewhere, Heineken Cup holders Toulon tackle Cardiff Blues at the Allianz Riviera Stadium in Nice on Saturday knowing that victory could confirm a last-eight place as Pool Two winners.

They lost in the Welsh capital three months ago, though, and the Blues are now just two points behind them, so there can be no room for complacency.

"We know what the challenge is all about," Blues boss Phil Davies said.

"We know it is going to be physical, and mentally we have got to be switched on.

"It will be the toughest game we have had this season, but we are in pretty good shape going into it, so the players are confident and motivated.

"We want to try to set up an opportunity to come to the last pool game at home against Exeter next week with lots to play for."

Exeter host Glasgow on Saturday, while Sunday's action features a Pool Three showdown between Toulouse and Saracens, with Northampton visiting the Ospreys and Leinster visiting Castres in Pool Two encounters.

Leinster will finish top of the group if they win and Saints come unstuck in Swansea.